title: Inhibitor κB kinase 2 is a myosin light chain kinase in vascular smooth muscle.
abstract: BACKGROUND
  Myosin light chain (MLC) phosphorylation determines vascular contractile status. In addition to the classic Ca²⁺-dependent MLC kinase (MLCK), another unidentified kinase(s) also contributes to MLC phosphorylation in living cells. Inhibitor κB kinase 2 (IKK2)-deficient mouse embryonic fibroblasts demonstrate abnormal morphology and migration, suggesting that IKK2 may be involved in MLC phosphorylation.
  
  
  OBJECTIVE
  Therefore, we tested whether IKK2 is an MLCK in living cells and the role of IKK2 in mediating vasoconstriction and blood pressure regulation.
  
  
  RESULTS
  In the present study, we showed that recombinant IKK2-phosphorylated MLC and intact myosin in vitro, and the kinetic parameters were comparable with those of the classic MLCK. Overexpression of IKK2 increased cellular MLC phosphorylation level, and pharmacological inhibition of IKK2 markedly decreased vascular smooth muscle cell MLC phosphorylation, suggesting that IKK2 is an MLCK in living cells. IKK2 inhibitors dose- and time-dependently attenuated vasoconstriction elicited by diverse agonists, suggesting the physiological importance of IKK2 as an MLCK. Vascular smooth muscle cell-specific IKK2-deficient mice had decreased aortic contractile responses, and reduced hypertensive responses to several vasoconstrictors, compared with wild-type mice, confirming the physiological importance of IKK2 as an MLCK.
  
  
  CONCLUSIONS
  Our data provide a novel mechanism whereby IKK2 regulates MLC phosphorylation as an MLCK and, thus, vascular function and blood pressure.
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA. yingzhekang@hotmail.com
authors.forename: Zhekang
authors.initials: Z
authors.lastname: Ying
authors.forename: Jussara M
authors.initials: JM
authors.lastname: do Carmo
authors.forename: Lusha
authors.initials: L
authors.lastname: Xiang
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: da Silva
authors.forename: Minjie
authors.initials: M
authors.lastname: Chen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ryan
authors.forename: Michael
authors.initials: M
authors.lastname: Ostrowski
authors.forename: Sanjay
authors.initials: S
authors.lastname: Rajagopalan
authors.forename: John E
authors.initials: JE
authors.lastname: Hall
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D003433:Crosses, Genetic; D003872:Dermatitis / Q000201:enzymology / Q000235:genetics; D006801:Humans; D051550:I-kappa B Kinase / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology; D018994:Myosin Light Chains / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D017207:Rats, Sprague-Dawley; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000172:deficiency / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013876:Thiophenes / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D018994:Myosin Light Chains; D010446:Peptide Fragments; D047888:Receptors, Tumor Necrosis Factor, Type I; D011993:Recombinant Fusion Proteins; C477523:SC 514; D013876:Thiophenes; C506236:Tnfrsf1a protein, mouse; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; D009219:Myosin-Light-Chain Kinase; D009218:Myosins
keywords: IKK2; MLC; blood pressure; blood vessels; hypertension; muscle, smooth, vascular; myosins; phosphorylation